8 – Can not add a file with attachments from the search API

I'm using Search API with Solr and Tika under D8 to create a search engine on my website.

I did not find any tutorials under D8 for this, so I followed the one I found on D7. However, when I try to add a "file" field to my index, it appears in a section called "Ignored Fields" with the following message:

The following fields can not be indexed because there is no type mapping
for them:

Source ┬╗File (type" entity: file ")

If you think that one of these fields should be available for indexing,
report it in the queue of the module. (Make sure first
search for an existing number for this field.) Please note that
Entity value fields can usually be indexed by indexing their
parent reference field or their child entity ID field.

Has anyone managed to index files using API search attachments? I do not understand how to solve this message.

Moreover, it makes no sense to "index their parent reference field" as this will put an identifier in Solr, and not a true text file metadata.