You cannot prepare a submission if you did not submit your Intent to Bid by the outlined deadline. You can find the deadline to submit your Intent to Bid on the Project page under Important Events.
If the deadline has passed, you receive the following message: "You cannot prepare a submission because you did not submit your Intent to by [...]".
Euna Procurement Support does not have permission to extend, edit, or manipulate any Project schedules on the buying organization's behalf. Reach out to the Project Owner directly (refer to How do I contact the Project Owner?).