Follow these steps below to install Manta theme via FTP:

Step 1. Login your FTP account via FTP software to access your host web server.

Step 2. Extract file.

Step 3. Upload the extracted folder manta to wp-content/themes folder.

Step 4. Activate Manta theme in Dashboard > Appearance > Themes.

Step 5. Install and activate Thim Core plugin of Manta that required for importing demo data.