https://github.com/anatolkin-s/anatolkin-mosaic-gallery#readme - the link to the latest version of README.

Installation & Update Guide

for Anatolkin Mosaic Gallery

1. Fresh installation

1.1. Before you start (recommended)

• Make a file backup of your TYPO3 project.
• Make a database backup (via phpMyAdmin or mysqldump).

1.2. Install via Composer (recommended)

Use this if your TYPO3 instance is managed with Composer.

1. Go to your TYPO3 project root (where composer.json is located), for example:

   cd /var/www/typo3/typo3-site

2. Run Composer as the same user that runs your web server/PHP (e.g. www-data on Ubuntu/Debian):

   sudo -u www-data -H composer require anatolkin/anatolkin-mosaic-gallery:^0.1

3. Wait until Composer finishes (no errors).

1.3. Install without Composer (TER / .zip)

Use this if you manage extensions via the TYPO3 Extension Manager.

Option A: From TER

1. Log in to the TYPO3 backend as admin.
2. Go to Admin Tools → Extensions.
3. Switch to Get Extensions.
4. Search for Anatolkin Mosaic Gallery or anatolkin.
5. Click Import and Install.

Option B: Upload .zip

1. Download the .zip package of the extension (from TER or GitHub).
2. In Admin Tools → Extensions click Upload Extension (.zip).
3. Select the file and upload it. TYPO3 will install the extension.

1.4. Activate the extension and TypoScript

1. In Admin Tools → Extensions
   • Find Anatolkin Mosaic Gallery
   • Make sure it is activated (green status).
2. In Web → Template
   • Select your root page.
   • Choose Info/Modify → Edit the whole template record.
   • On the Includes tab, add
     “Anatolkin Mosaic Gallery (anatolkin_mosaic_gallery)” to the Included static templates list.
   • Save.

1.5. Clear caches

Pick any method you like:

• Backend button: click the Flush cache (lightning/fridge) icon in the top bar.
• Maintenance module: Admin Tools → Maintenance → Flush cache(s).

• CLI (Composer installs):

  cd /path/to/your/typo3-project sudo -u www-data -H php vendor/bin/typo3 cache:flush

1.6. Quick check

• In Admin Tools → Extensions the extension shows up with version like 0.1.12 and is active.
• In Web → Page → [some page] → + Content → Plugins you can add the
  Anatolkin Mosaic Gallery plugin to a content element.

If both are true, the extension is installed correctly.

2. Updating to a newer version

2.1. Before update

• Make a database and file backup (same as for fresh install).

2.2. Update via Composer

1. Go to your TYPO3 project root:

   cd /var/www/typo3/typo3-site

2. Update the package:

   sudo -u www-data -H composer update anatolkin/anatolkin-mosaic-gallery # 
   or explicitly: 
   sudo -u www-data -H composer require anatolkin/anatolkin-mosaic-gallery:^0.1

3. Clear caches (see section 1.5).
4. (Optional) If future versions add database changes:
   run Analyze Database Structure in the Install Tool and apply suggested changes.

2.3. Update via TER / .zip

1. In Admin Tools → Extensions:
   • either click Update next to the extension (if available),
   • or upload the new .zip file via Upload Extension (.zip).
2. Clear caches (section 1.5).
3. (Optional) Run Analyze Database Structure in the Install Tool.

I’d be happy to hear your feedback, ideas, or suggestions for future features. 
If you find this extension useful, any kind of support or contribution is greatly appreciated.