Hello! I am trying to install Zorin OS in dual boot with windows. This is not the first time I try this (tried with other distros), but zorin is asking me for the bootloader location. Now, I have no clue what to select. Reading online I figured that it depends if my computer has BIOS or uefi, mine has uefi but other than this I couldn't figure out more.
Any help would be appreciated, thank you.
I have in the past just left the selection alone. I believe it defaults to the main disk and that disk should have a UEFI partition.
If you choose the main disk it will show options for windows boot and zorin boot, if you choose the secondary drive you will have to adjust the boot order in order to get to zorin.
Unfortunately doesnt seem to work in my case, Zorin doesnt even get recognized by the bios (or whatever is called, not sure)
I am not sure which one the main disk is, is there any way to find out?
The main disk is always numbered the lowest. Then it's the partition number. When listed in gparted, the very top partition is the first partition on the first disk.
I tried to use the first option, the one with the lowest number, in my case it is dev/sda (with no numbers), but the bios doesn't even recognize Zorin as being installed, so not only grub isn't there but zorin in general and I don't really want to try each option because I don't want to mess up with my windows installation
So you intend to dual-boot alongside Windows.
How did you try to install Zorin. Did you use the "Something else" method?
Can you post a screenshot from Gparted, showing your disk partitions?
Maybe also take a look at this thread: USB boot install
If new to Linux and Zorin, @swarfendor437 's "Unofficial Manual for Zorin 15" is still available to download. See here: Unofficial Manual for Zorin 15
Dev/sda is the device (first hard drive). It should be sda0p0, but every Bios is different and may number yours differently. If you post a screen shot of your hard drive/ partition selection screen i may be able to tell you which one.
You should do a little more research into hard drive partitioning to understand what is going on and why it's important to place grub in the first drive on gpt partitioned hard drive. That understanding will also help you with your decision, which drive and partition to choose for grub and what the purpose is for each partition.
More information is needed - Windows 10? My advice is you follow Matthew Moore's tutorial video - there is also an issue of whether we are dealing with more than one hard drive such as Asus Zen books that have an SSD for the Windows 10 OS and an HDD for the Data.
Yes, I used the "Something Else" option.
What I did is first making some free space in a hard disk that is different from where windows is installed (a D: drive as windows calls it) and then I followed a tutorial I had used for another linux distro. I created a home, swap and boot partitions and then when the installation finished I restarted and grub wasn't there at all.
I had the same issue. I fixed that with another boot to live USB, and than used grub fixer.. Weird
Regarding the options I have here is a list:
/dev/sda -- Probably My D drive, because the free space I made is under this (Windows is not located here)
/dev/sda1
/dev/sdb
/dev/sdb1 -- Windows Boot Manager
/dev/sdb2
/dev/sdb3
/dev/sdb4
/dev/sdc -- Live USB (There is the usb name right next to it)
Any idea?
Will try this of no one can suggest any other way
Gparted gives a little more info, unless you labeled your windows partition it won't say it is. There should be a partition at the beginning of the drive before the windows boot partition. My guess is that it wasn't created or created in another part of the drive, probably on sdb. Go into the bios and check the boot order for an Ubuntu boot option. If it's there you will have to switch boot order to boot into zorin.
A way to fix this is rerun the installation, don't format, and read carefully to change the boot location. When you get to that part choose the windows boot partition. Then you can delete the other boot partition when you load up zorin without causing any more issues.
For all here, I have solved this. Just install the bootloader in EFI partition where it says windows boot manager. It worked for me.
Thanks man, this worked for me too! 
As a note, this does overwrite your windows boot manager. If you are trying to add a grub partition without modifying the windows boot manager, you would have to create a separate partition for grub, and ensure grub is installed there.