Update question

Today I received the information from Envato that your plugin has an update and I should download it.
Why should I do it in such a crooked way? Why your plugin cannot be updated through the WP dashboard like all other plugins do?

WP today informs me that there is an update exists
“You have version 1.0.1.1 installed. Update to 1.0.1.2. View version 1.0.1.2 details.”
Unfortunately, I failed to update it.
WP returns with the notification explaining that there is an error:
“An error occurred while updating Sales Countdown Timer Premium for WooCommerce and WordPress: Update package not available.”

Why the simple update process so complicated?