First, download the Nextcloud program for your operating system:
https://nextcloud.com/install/#install-clients
Launch the installer and follow the installation wizard
You will be prompted to pick a folder on your own computer to store your files.
You will also be prompted to enter the server address for your Nextcloud installation, which is:
Enter your May First username and password.
Your web browser will open and prompt you to login into share.mayfirst.org if you have not already done so. Enter your username and password in your web browser and grant access. After you did that, go back to the wizard.
Select which remote folders to sync, and which local folder to store them in.
On the local folder options screen, you may sync all of your files on the Nextcloud server, or select individual folders. The default local sync folder is Nextcloud, in your home directory. You may change this as well.
When you have completed selecting your sync folders, click the Connect button at the bottom right. The client will attempt to connect to your Nextcloud server, and when it is successful, the wizard closes itself. You can now observe the sync activity if you open the main dialogue by clicking on the tray icon.