Here is St Louis De Montfort…
14.
That is entirely correct.
And the same St. Louis said:
"Her prayers and requests are so powerful with him that he accepts them as commands in the sense that he never resists his dear mother’s prayer because it is always humble and conformed to his will."
(That should be a sufficient explanation also of what St. Alphonsus meant.)
And:
“She is so full of love that no one who asks for her intercession is rejected, no matter how sinful he may be. The saints say that it has never been known since the world began that anyone had recourse to our Blessed Lady, with trust and perseverance, and was rejected. Her power is so great that her prayers are never refused. She has but to appear in prayer before her Son and he at once welcomes her and grants her requests. He is always lovingly conquered by the prayers of the dear Mother who bore him and nourished him.”
(True Devotion 27, 85)
The quote you gave and these two quotes do not contradict.
When people praise the greatness of Mary, they are not implying that she is greater than or equal to God, nor are they implying that she is the origin of her own greatness. We don’t need to diminish her every time we say something good (and true) about her.
Rather, she is so great as to be completely beyond our comprehension, that if any one of us knew even a fraction of her greatness, if it wasn’t for the Church teaching us that she is not herself God, we would probably mistake her for being God.
Compared to her, we are nothing; but compared to God, she is nothing.
Also, concerning jealousy toward Mary, if that applies to anyone.
It is not simply because God was super nice to her that she is greater than all creation combined. She was entrusted with bearing the Son of God. No one has ever been given a task more important or more difficult. She isn’t called Mother of Sorrows for nothing!
“Yet, if I were to see thee now, in majesty stupendous,
Surpassing all the crowned saints in highest heaven above,
Scarce could I dream I am thy child, (O truth sublime, tremendous!),
For I should think myself to be unworthy of thy love.
The mother, who desires to be her child’s best earthly treasure,
Must ever share its grief with it, must understand its pain.
Queen of my heart! how many years, thy sorrows had no measure;
What bitter tears thine eyes have shed, my worthless heart to gain!
So, musing on thy earthly life, in Scripture’s sacred story,
I dare to look upon thy face, and unto thee draw nigh;
For when I see thee suffering, — concealed thy marvelous glory —
It is not hard, then, to believe thy little child am I.”
St. Therese of Lisieux (Doctor of the Church), Why I Love Thee Mary