Several users can work with a single database file simultaneously. Changes, made from different devices, will be merged in one file.
Enable synchronization in the app settings, enter your Dropbox account details (if you don't have an account, you can create one for free), then tap "Allow" to connect the database to Dropbox. Now send the database file to your family or colleagues (e.g via email or WhatsApp), to do this tap on Share button in "Overview" tab near the database name. All changes they're making in their copy will appear on your device within a few seconds and vice versa.
Sync works via Dropbox cloud service. Each database file must be connected to Dropbox separately, so you can use different accounts for different files. If you don't have account, you can create one for free. It's not necessary to install Dropbox app on your phone or share your Dropbox account password. If you have Dropbox app but want to use another account simply tap "Use a different account" button.
Sync via iCloud
Put your database file into iCloud Drive and all changes you've made will appear on other devices and vice versa: changes are made by other users will appear in the program within a few minutes.
To share a budget with family or colleague tap on the Share button, then tap "Add people" (if there is no button, this means that the file isn't located in iCloud Drive). The file will appear in the other users iCloud and they'll be able to make changes (if allowed) and see the changes are made by other users.
To work with the database file on a PC simply download and install iCloud Drive app for Windows and cloud contents will appear on your PC as a common folder. Then download and install Alzex Finance for PC (version for Mac OS is also available), find your file in the cloud and open it (double click or main menu File - Open).
Share a budget via other cloud services, local network, own server, etc.
The Files app lets you add third-party cloud services and apps that provide access to local networks, FTP-servers, NAS and so on. Download and set up a third-party app, then enable it in the "Locations".
To share a budget with other users follow the instructions of the corresponding cloud service.
Sometimes a conflicted copy of the file can appear, simply delete it (your changes won't loss).
Google team doesn't like easy ways (or Apple users). Database file located in Google Drive can be opened only in the Files app.