As explained in chat and in case anyone else has this question in the future: The method below is the current way to claim and force load chunks in modpacks v1.18+ that have the FTB Teams mod in the pack: Open the map by pressing (usually) 'M'. This will open the map. In the top left corner (might be at a different location for other packs / newer FTB Teams versions) there will be a small map icon. Click on that icon to open the chunk manager interface. Within the chunk manager you are able to claim chunks and force load chunks. By simply left clicking a chunk it will claim the chunk you clicked and will prevent others from doing things on it. In case you want someone else or another party to be able to interact with the chunks, you will need to ally the person / FTB team within the FTB Party Manager omterface. The FTB Teams Manager interface can be pressed by opening your inventory and heading towards the icon with 3 body outlines. This will open the party manager. By then going to the top right of this interface it will allow you to open the 'Manage Allies' interface. By holding down shift and left clicking a chunk it will force load a chunk. This chunk will stay loaded while you're away from your base or might keep the chunk loaded offline if the version allows it. TL;DR: to claim chunks and load chunks in modpacks v1.18+ that have FTB Teams: open the map (usually key 'M'), head towards the top left corner to open the chunk manager interface. Left clicking will claim chunks and shift + left click will force load chunks.
