GNU/Linux Mint 20 TP-Link Archer T3U AC1300 Driver Setup – Step-by-step Guide
The linked tutorial shows you step-by-step How to Install TP-Link Archer T3U AC1300 USB Adapter Wireless Driver in GNU/Linux Mint 20.x Ulyana/Ulyssa/Uma/Una desktop.
And the TP-Link Archer T3U AC1300 Dongle make use of the Realtek rtl88x2BU Chipset.
Especially relevant, in case to check your Adapter Chipset see: How to Check Wireless Device ID on GNU/Linux.

Installing Realtek rtl88x2BU Driver on Mint