What to keep in a presentation intended towards invited collaboration?
I am changing your question title from "What to keep in a collaborative presentation?" to "What to keep in a presentation intended towards invited collaboration?"

Note that they already have followed you for a while or probably had an informal chat with you in a conference or meeting. So, they know what kinds of work you are doing. Just keep the following:


Broad topics of research works that your lab is doing
Possible sub-topics under each heading
Recent outcomes under each sub-topics.
Your Lab (research students, post-docs, peers ...)
Your Lab (environment available, required if that university is interested in sending their student for short-term research)


Total 15 slides is good enough. Depends on time they have given you. This would suffice, I guess.