Thank you for all your feedback!
We are now working on supporting external user access within Planner, we will update this thread as soon as it is available.Anonymous commented
I did the same as you; added a external person to a shared One Drive area. Then I added the person to the actual plan and was able to assign tasks to that member.
I work with external users that come from both big companies as well as "one" man companies. The big companies are usually no problem regarding licens, but the small companies are more concerned about licens.
The question I have; What kind of licens must that person have? Are there any "free" licence with limited access? Or does everybody has to have the Enterprise licens?