Bearer Token Returned gives a 401 error

Hello,

Using the tutorial at this link https://portal.azure.com/#blade/Microsoft_AAD_RegisteredApps/ApplicationMenuBlade/Quickstart/appId/a23a4412-9f4b-4876-90b0-8969ddb0c03b/objectId/0349d43d-ddd6-4cae-86d2-e08f502cbe3c/isMSAApp/

I am given a bearer token. When taking this bearer token and using it on Postman, I get a 401 error. I am trying to gain access to use the api to take actions on a blockchain application. Any help would be nice because of our deadline coming up soon

Thanks