Although there might be significant differences between each different blockchain, as a general principle, they are certainly not intended to store media content by design.
As for the textual content, you can store it in the blockchain but you have to manage all the encryption in order to restrict who can access to it, and it can be somehow complex if data can be retrieved by different groups of users (if this would only be peer to peer, you could use asymmetric encryption). I am assuming you would be using a private blockchain without gas fees per transaction; otherwise, the approach would be unfeasible in case of a high volume of communications.
One way you could use the blockchain is to manage the data access: when you provide tokens to users, these tokens could be used as a pass to access data (either text or media) which is stored off-chain (out of the blockchain, for instance, in Azure).
Just as a reference, the closest thing for managing text communication using a blockchain is the project Status, but I am aware it took a few years for them to reach a production-ready application. Perhaps you can also get some ideas from there.