When I call API , why response 401?

I used postman to call the API https://sonarcloud.io/api/components/show?component=Exonumia, and I used base auth
my token is 6dxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxd0, and encode base64,
get NmQ3M2xxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxxFkMDo=,
use this encode token set to Username field, and Password set null, and send request, I got 401, so why ?

The VALUE used in the header Authorization: Basic VALUE is not simply the base64 encoded token, but the token followed by a :. For example, if token is foo, the value should be Zm9vOg==, not Zm9v.

If this doesn’t help, please share the exact command you use (with a dummy token), and the Authorization header line of your request.