The UI should be updated to look similar to Microsoft Teams and remain responsive across all devices.
Your design MUST work with all the functionalities of the script and you will be required to ensure the UI is mapped to all features. You also must be able to design freely without solid mockups being provided (except UI guidance of what the UI should look similar to - Microsoft Teams).
20 freelancers are bidding on average $588 for this job
Having developed the UI for multiple high growth and respected startups as an engineering lead (carwow, MEDWING), I believe to have the experience you are looking for.