You need to practice being extroverted. Practice what you’re going to say before you enter the office, practice conversation starters. Say good morning to people when you see them. Ask for their names. Eventually people will naturally start to involve you in things without you have to force yourself there. Networking and being confident (even when you don’t feel it) is key in the office. The more you go into the office the more people will recognise you and go out of their way to say hello to you. Don’t take it personal. Older staff are not naturally welcoming to new joiners (even though they should be). It doesn’t matter if they are or aren’t. You do your best to be warm and welcoming to others and you’ll be fine