For this adapter, according to Wireless Wiki [1], you should use
universal driver "rtl8xxxu". See if it was loaded:
$ sudo lsusb -t
Check out the logs for relevant messages:
$ sudo grep -iE "rtl|firmware" /var/log/syslog
This should give you a hint about a firmware file needed for this adapter.
Probably it is a good idea in general to install firmware package for
Realtek-based devices from "non-free" section of Debian repos:
$ sudo apt install firmware-realtek
[1] https://wireless.wiki.kernel.org/en/users/drivers/rtl819x
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With kindest regards, Alexander.