Installation on ubuntu does not work correctly

[dido48]

The error is:
{"error":"illegal_database_name","reason":"Name: '_fti'. Only lowercase characters (a-z), digits (0-9), and any of the characters _, $, (, ), +, -, and / are allowed. Must begin with a letter."}

I have done everything that was described here - https://smartregister.atlassian.net/wiki/spaces/Documentation/pages/33259522/CouchDB-Lucene+installation+guideline+for+Full-Text+search

and in the comments I saw that this errors that I receive is very often