Welcome to the community!
What type of plan do you have or are trying to activate? As far as I am aware, the activation of pre-paid SIM cards can only be done in-store (see here). If you're trying to update your SIM card, you should be able to do so via My Account.
I'm not sure if there are any provisions for the activation of pre-paid SIM cards during Covid-19. You might consider contacting customer service to see your options. Alternatively, you might consider sending @FidoSolutions a PM. They might be able to offer a means to activate the SIM through them.
Hope this helps 😀