If unable to connect to the net, then any downloading, installing from the net or updating from the net will not yet be possible.
If you cannot connect using either Mobile Hotspot, Ethernet or WiFi; your best bet is to download the files you need and transfer them with a USB stick.
Open a terminal In the directory that contains those files.
In this case, within the RTL88x2BU-Linux-Driver directory. Some file managers allow Right Click > Open In Terminal to do this.
Or you can Change Directory (cd command) in the terminal to reach that directory. For example, if you transfer the file into your Downloads folder..
cd ~/Downloads/RTL88x2BU-Linux-Driver-master
Then run
/.configure
make
sudo make install



