How to co-author on Excel workbooks?

Hi,

Wonder if any one else experienced this issues, I also followed this link but still not able to get it fixed: https://support.office.com/en-us/article/collaborate-on-excel-workbooks-at-the-same-time-with-co-authoring-7152aa8b-b791-414c-a3bb-3024e46fb104

Scenario: (Note * Used 2 different users, not the same user)

I’ve added a excel document on my sharepoint document library.

I’ve opened it on the first users pc and got the “read only” message but opened it fine.

I’ve opened that same document on another users pc and got the same “read only” error but with more details.

After clicking on the “read only” I got a message that states the document been used by another user, I have the option to view it as read only or save it locally, don’t want one of those options, want to edit the doc on both pc, different users on the same time?

Any ideas, something I’m missing?

Note * I’ve checked with Word and it works perfect without any issues.

Thanks.

I can also add, I’ve tried different file extensions, ie: .xlsx, .xlsm & .xlsb and also the office versions is on the same version ending 2295 and both is office 365 pro.