Hi Venessa, an important thing to note, CASL requires a Double-Optin to be compliant, the processes described above are a single optin. You will need to send an email asking them to confirm consent (not pre-checked), only then can you legally email. Granted you have qute a bit of leway for existing business relationships and 3 years to comply, but best to set it up correctly from the begining.
The flow Id use would be
Yes I want to recieve emails. Then instead of sending them to the thank you page you would state, "We have sent you an email confirmation, etc... Please confirm your consent by checking the Yes I granted Permission check box." Once they check that box then you can send them to the thank you for providing your consent. That way you have a reciept and timespam of their consent.
Ps same rule applies or Germany btw.