You confuse me with the term '5G network'. Please be careful about terminology.
You do not have a 5G network.
Comcast has talked about a 5G network. Just empty talk.
About that adapter. It is not a 5G adapter.
It can operate on the 5 GHz band. Which might help. Or not.
It is overpriced if you buy t for more than $30. IMO.
What does Comcast say? Do they offer speeds over 54Mbps?
Adapters like the one you bought can be found with Google.
wifi 801.11ac adapter... will find many under $30.
The 801.11ac adapters are compatible with early 801.11xx standards.