I installed rtl88x2BU on a new installation of MINT 19.3 (kernel 126.96.36.199), source: github cilynx/rtl88x2BU_WiFi_linux_v5.3.1_27678.20180430_COEX20180427-5959, using the README.md instuctions for DKMS installation.
I can only connect to non-encrypted ssid's. When using an encrypted ssid it fails to establish the link.
Since I had installed the module before while plugged-in the usb device I cleared the installation using
sudo rmod 88x2bu
and repeated the installation successfully but with the problem that I cannot connect to a WPA / WPA2 personal protected ssid.