CRM for just the relationship part, not the sales

As the title, I’m looking for a CRM that will allow teams to manage relationships with external collaborators (academic) that might run over several years. Not focussed on sales at all though, just on managing the relationships, keeping track of activities and objectives and providing overall internal team transparency. It currently runs via emails, excel sheets, PowerPoint updates and an air of mystery – and it’s horrible.

Ideally with a very shallow learning curve for an internal team of technological luddites.

Edit: Integration with O365 (which we have to use) would be a big plus.