Anyone who believes in Jesus has satisfied the condition for being filled with the Holy Spirit.

Infact, the believer receives the Holy Spirit when s/he believes. "Being filled" means to consciously activate the flow of the gifts of that spirit already in you.

Consider the verses below.

On the last day, that great day of the feast, Jesus stood and cried out, saying, “If anyone thirsts, let him come to Me and drink. He who believes in Me, as the Scripture has said, out of his heart will flow rivers of living water.” But this He spoke concerning the Spirit, whom those believing in Him would receive; for the Holy Spirit was not yet given, because Jesus was not yet glorified.
John 7:37‭-‬39 NKJV

Note that the only condition to be filled is to believe and "thirst". It is for anyone (not for some only but for anyone and everyone) that believes and desires.

Thank God that Jesus is now glorified and the Holy Spirit given. Matthew 28:18, Philippians 2:5-10 Acts 2.

If you're a believer and are not "filled with the spirit", what is really the matter

I met a couple who had believed for over 15 years but were not yet "filled ". They desired it. They had prayed and even asked people with big titles to pray for, and with, them that they might be filled to no avail. They even fasted and were placed on fast by some.

All it took was about 15 minutes of explaining God's word to them and they both spoke. The husband spoke in tongues, sang in tongues and also interpreted the same day! Glory to God!!!

If you are a Christian and you are not filled with the Holy Spirit, what is the problem or what are you waiting for? Are you waiting for when you get to heaven or what?

For those who desire to drink of the spirit, it's available and also free.