The client receives a link, reads the contract to the end, then signs. No account, no app: one page, and a code sent to the address that received the contract.
Signing: identity, drawing, code
First name, last name, email, place and date, then the signature drawn with a finger, mouse or stylus. A code goes out by email; entering it and ticking the consent signs the contract.
Not signing
Refusal is provided for as much as agreement: a reason if the client wishes, and the provider is told. They can send the contract again if the client changes their mind.
What is collected, written out plainly
At the moment they are asked, the client reads what is recorded, why, on which legal basis, for how long, and whom to write to for access. A fingerprint of the document, at the bottom, guarantees its text has not changed since it was sent.