How to install theme in Magento 2

Download the theme and copy the app folder and paste it in your magento root directory

1. Open Shell, in the root directory, enter php bin/magento  setup:upgrade . This will upgrade all the magento files.

2. Also, Clear cache ,type  php bin/magento  cache:clean . 

3. Now force deploy the static files by typing  php bin/magento  setup:static-content:deploy -f . It will take a while.

4. Now, Go in the dashboard and select content->configuration.

5. Select the option with default store view and edit.

6. Select your theme from the options and click save and edit. If some problem arises, go to the vendor/magento/module-email/Model/AbstractTemplate.php and comment the “if”  condition of “setForcedArea” function, aprox. at line 535.

7. After changing theme successfully, clear the cache as done before.

Voila, the theme is changed!!