Hi @Patrick_van_der_Valk, thanks for reaching out! Adding to what @Bastien_Siebman mentioned, if the project templates are private, please make sure to set them as public before you leave the company. In regards to the task assigned to you, in Premium Organizations, a private project will be created for the Admin containing both public and private tasks previously assigned to the you after you are deprovisioned. You can find more details in the article below:
If you Admins have issues to access any projects or tasks, you can advise them to contact our support team: How to contact our Support Team ✉
I hope this helps!