If you haven't yet, try booting from USB again and clicking through to "try" Zorin instead of install it, then run the Boot Repair software. Hopefully it will fix your bootloader, but if not it should give you an error message that might help find a solution.
I've seen i386 errors around occasionally, but it confuses me as Zorin dropped support for 32bit systems a while ago - of course it doesn't install 32bit grub files!
Out of interest, is your Windows 10 installed as 64bit or 32bit? Some devices of that era have mixed bit-depth hardware, where the CPU is 64bit but the BIOS / UEFI are 32bit and so aren't supported by a lot of modern linuxi including Ubuntu (which Zorin is based on).
Also, according to this Acer community post, the 5750g uses MBR and legacy BIOS, does not support GPT and UEFI. You may need to boot into the installed Zorin (Super Grub2 Disk can help with this) and then flip grub from EFI to MBR as in this guide:
P.S. especially if you only have one USB stick, if it's 16GB+, I recommend flashing it with Ventoy. That way you can copy multiple ISO files onto it and boot any of them, without having to keep re-flashing the drive with only a single ISO. This allows you to keep a few linux live environments and other tools like SG2D and Clonezilla to hand and immediately usable.