Q:

What is the Get URL to fetch TEAM roster or user profile information? 

Can someone please share the postman to fetch TEAM roster or user profile information.  I am referring to https://docs.microsoft.com/en-us/microsoftteams/platform/bots/how-to/get-teams-context?tabs=json

A:

The Url you need is this: [serviceUrl] + "/v3/conversations/{teamId}/members/"
and it is based on two variables: the "teamId" is obviously different per team.  However, the first part of the address (called the ServiceUrl) can also vary between teams, based on where they might be hosted, and you need both. 
It sounds like, from the link you sent, that you already have a bot?  If so, your bot can retrieve both of these required parameters.  One way is that, whenever a user sends a message to the bot, to get the ServiceUrl and TeamId that are sent in the incoming "activity" object that.  However, if you want it even earlier than this (i.e. before a user even sends a message to the bot), have a look at the conversationUpdate event here which will fire right when the bot is first added to the conversation. 
Does that help?