small-ERP system for Room Rental

Looking for a sleek, within budget, mobile and web app for the internal management of our company. Somewhat an in-house SaaS. It is suppose to be an could tool that works online and offline (syncing it asap), available as web app and mobile app (android); for use on laptop, tablet and phone. Configured in AWS, Azure, Google Cloud or alike. The application shall be robust and yet easy to extend or add new functionalities. A thorough and easily readable Manual of Configuration shall be made available too. Deliverables shall include, but not limited to, for the "Dashboard": a) Dashboard (similar to excel template, showing a set of data) b) Occupancy Calendar c) Forms and internal management All points mentioned above are interlinked and will require a database containing: - Landlord ID (basic and advanced info, Building ID, Rooms ID, Tenant ID, signed contract, signed forms (including T&Cs, inventory, price rates), special requirements, monthly rate, bank account, etc) - Building ID (Landlord ID, location, monthly costs, management costs, cleaning costs, status, condition, ROI, number of rooms, room ID) - Rooms ID (price, room typology, payment date, deposit, inventory, document attachment, tenant ID) - Tenant ID (basic and advanced info, signed contract, signed forms (including T&Cs, inventory, price rates), special requirements, monthly rate, date of payment, deposit, bank account, university & course, etc) - Candidate ID (application form, basic and advanced info, booking/visit appointment, etc) - Staff ID (basic and advanced info, daily agenda, booking/visit appointments, closed deals, etc) All forms should be editable and customisable; generate, stored and signed within the system whether on a tablet, phone or computer. Ideally should have functionality to extract to excel and PDF when required. Some will be with tick boxes, other with text, some may require pictures to be attached, etc. For example: the "Welcome-In Inventory List" should be similar to what you do when you rent a car and are doing the checking that it is in the right condition. Already have hosting domain. We expect a pretty simple and straightforward requirement, within budget. Sleek look and very interactive (easy to use) will be a must.