Service request form with Automation

Looking to replicate a sharepoint/powerapps form that utilizes logic and prepopulates fields based on dropdown selections. The form data needs to be stored in a way that allows the data to populate a viewable calendar and/spreadsheet view. The workflow is currently as such. Form submission triggers an email to a salesperson, the salesperson reviews the submission and assigns a team member. This triggers an email to the team member that allows them to accept/deny the work. If they accept, it triggers emails to notify the salesperson and the original submitter that the work is scheduled. It also triggers the data to send to the spreadsheet and create the calendar entry. I can do a walk-through of the form and the powerapps piece. Our only issue is that the workflows occasionally fail and that the users are outside of the organization. Licensing is too costly to warrant the use of sharepoint/powerapps. Looking for something custom, perhaps with WordPress or web app.