How to make a Discord application form bot for staff applications

Steps

Make a staff channel and a role
Create a private channel such as applications for staff, and the role an accepted member should get.
Start from the applications template
Open the applications template in Buildcord. It makes a bot with the Apply button, the form, the staff post and the Accept and Deny buttons.
Write your questions
On the Modals page, change the form's questions. Each can be a short answer or a paragraph, and can be required.
Decide what Accept does
In the Accept button's flow, set the role to give in the Add role step and the message the member receives. Deny sends its own message.
Deploy and post the panel
Paste your token, deploy and post the Apply panel where members will find it. Apply from a test account and accept yourself.

Discord allows up to five questions in one form. For more, send a second form after the first.
Save each application to a collection with an Add row step to keep a record of who applied and what was decided.
Put the bot's role above the role it gives, or Discord won't let it hand it out.
For private conversations with staff instead of a form, the ticket system fits better.

Is the application form free?

Yes. Buttons and forms run on the Free plan, hosted around the clock.

Can I stop people applying twice?

Yes. Save each applicant in a collection and check it with a Find rows step before the form opens, or add a Cooldown step.

Can staff give a reason when they deny someone?

Yes. Have the Deny button open a short form for the reason, and include the answer in the message the member gets.