Hello,
the plugin can insert code only where your theme calls appropriate WordPress hooks.
This is clearly described on documentation pages:
https://adinserter.pro/documentation/automatic-insertion
You can easily check available positions for your theme:
https://adinserter.pro/documentation/automatic-insertion#available-positions
You can also visualize available insertion positions:
https://adinserter.pro/documentation/debugging
Therefore, if some insertion position is not available has nothing to do with the plugin.
It may also happen that the theme calls WP hooks but not where they would be needed to insert ads or other code.
However, for such cases the plugin supports also insertion before/after any HTML element:
https://adinserter.pro/documentation/automatic-insertion#before-after-html-element
You only need to find right CSS selectors that work with your theme.
If you need help with settings please submit a support ticket, refer to this thread and we’ll try to help you.