Two platforms; one account
Yes!
The event platform has been created by Unissu, so whether you sign up via the event platform or Unissu, you will end up with a Unissu account.
If you sign up to the event you will automatically be given a Unissu account via the sign-up process.
If you already have a Unissu account, you can simply sign into the event platform using your Unissu details.