Adding chatbot to our intranet to use our data

I manage an invitation-only intranet for about 900 users. They collaborate on business activities via this intranet. They upload PDFs, PPTs, and enter data about their activities. I’m looking into options to add a chatbot into the intranet for those 900 users, so they can use AI to query our private data, both from our database and those PDFs, PPTs, etc.

I was considering an Enterprise licence and use the API so that I can have the chatbot interface within our site.
I was hoping to only use one Enterprise seat for this, with all 900 users going through that one seat. However, I think that might not work well as if everyone uses the same seat, then the conversation one user has would polute the conversation another user has, since they both go through the same seat. There could be no history either, since it would be impossible to know who should see which historical conversation if they all use the same seat. Unless I’m missing something here.

I want to avoid both the cost of everyone having a seat, but also the overhead of managing those 900 user accounts in ChatGPT.

I discussed this idea with ChatGPT itself, and it was encouraging on this, but I’d like to hear opinions.

An additional complication is that naturally I’d like the chatbot to be up to date, and that if a user chooses to delete a PDF or some data record, then the chatbot should stop using that as a source of truth. The PDF that is deleted from our intranet should be “deleted” from the chatbot’s knowledge.

The folder on our server that stores these PDFs, PPTs etc is 13Gb. I was hoping to avoid the need for a vector database. Since I saw that with ChatGPT Teams you can have it read from a Google drive folder, where you store PPTs, PDFs, etc, then it could perhaps do the same from a regular server folder.