There are some manual ways that you can copy chat into text or Word, but usually they require copying batches of the conversation and pasting, repeating the steps, and then copy/pasting the images after.
You can capture the whole conversation using the following method. (Please note that this does not work well with long conversations as it seems to start at the top and work it’s way down).
Install the gofullpage Chrome extension (not endorsed, nor supported by RRU Computer Services)
Go to Teams online and log in
Click on the chat I want to copy/archive/whatever you want to call it
Scroll to the top so that all the chat is loaded off the server
Change 'Chat' to 'Contacts' on the left
Activate the gofullpage extension
The first time you run the extension it will ask for certain permissions. Once you give permissions you need to run the extension again
Wait
Once the file has been created, it will be displayed on the screen. Click the download PDF icon to download a PDF version
We could stop there if that's enough. But we want to be able to search the resulting PDF later so... don't follow the instructions listed in the previous (internal) comment to save the PDF as text and manage the images separately etc. etc. Instead:
Open the PDF using Adobe Acrobat
Ctrl-F to search and type a word you can see on screen
(This isn't searchable so) Answer 'yes' when asked if you want to run the OCR scanner
Wait while that runs
You should see the word you're searching for highlighted now
Save the file