Someone at your company invites you, and ARC emails you a link. Opening it creates your account and puts you in the right home with the right role.

Accept it

Open the link in the email.
Check the page. It is headed Accept invitation and reads "You've been invited to join [your company].", with the role and email address the invite was sent for.
Select Accept invitation.
You're in — from now on you sign in with a 6-digit email code, not a password.

If your company has only just joined ARC

A new company sets ARC up before it goes live, and the invites it adds in that time are held back. You get yours once the company's first payment is through, so it can arrive some time after you were told to expect it. If you open a link that has not been sent yet, ARC says "This invitation hasn't been sent yet."

If you accept before your company is live, you land on a page headed Your home isn't live yet rather than a home dashboard. Come back once your company admin tells you ARC is open.

Invites don't last forever

Each link works once and expires. If yours has lapsed, ARC will tell you the invitation has expired or has already been used — it won't leave you guessing.

Ask whoever invited you — your company admin — to invite you again.

Don't forward your invite to a colleague. It carries your role and your home, and once used it's spent — the next person gets nothing and you've lost yours.

What happens next

Two things commonly happen straight after accepting, and neither means something has gone wrong:

"You're not assigned to this home." Your account exists but nobody has given you a home role yet. Ask your manager or company admin.
You're held at your profile. ARC needs your safer-recruitment record complete before you can open a young person's records. Parts of it are for your employer to fill in.