SharePoint List Access to resource is forbidden

This problem makes me crazy.  I run into all the time.  I never get to work in Power BI because I spend all my time just trying to get it. Then it gets put to the side for another six months -- I'm going on two years of this nonsense.  In February, I finally got a Microsoft expert to help me, we got in, by clearing the credentials.  I got in one other time and -- today -- the same problem has once again reared its ugly head  and I can't seem to get past it.  

1. I'm trying to access a SharePoint list
2. I've cleared all credentials as per my earlier instructions with Microsoft.  
3. I choose Web
4. I choose Organizational account 
5. I paste my URL
6. It says I'm not signed in
7. I choose Connect and it says the current user isn't signed in. 
8. I go back.
9. There is the URL with basic selected
10. I choose enter and it takes me back to Anonymous
11. I choose Organizational account 
12. This time I choose "Sign In"
13. Tells me I'm being signed in
14. I pick my organization account
15. Takes me to my sign in page and does the authentication
16. Now it says you are currently signed in -- which I have been all along and invites me to sign in as a different user. 
17. Just for the heck of it, I select sign in as a different user and I get Access_denied: Access denied.  

This is infuriating and a huge waste of my time to keep using a process that does not work.  Any ideas???  Please????????????