The AdaptiveMT capability is end-of-life (EOL) starting with December 1, 2021. This technology was still based on Statistical MT, which was deprecated starting with February 2020.

This decision is a natural next step in our translation technology evolution. Development and focus will be continued for Language Weaver's neural machine translation (NMT) innovation.

From December 1, 2021, you only the standard access to NMT will be available through Trados Studio (Generic - NMT models only). 
The Manage AdaptiveMT Models button will be grayed out in the Trados Studio 2021 UI and it will also be completely removed in a future update for the product.