In the Castle

G P
P G

B B
R R

P R
B G

R R
R R

The slider puzzle can be solved a few ways, the easiest way is up and then right.

Astilbe's when given to a beloved one means you will wait for them
Craspedia's mean good health
Zinnia's can mean constancy which means faithful and loyal
Forget-me-nots mean rememberance
Daffodils can mean rebirth

From the lyrics given,
"With DEDICATION and love I will PATIENTLY WAIT" -Astilbe
"Wishing you GOOD HEALTH" -Craspedia
"as I stay FAITHFUL for your RETURN." -Zinnia
"I WONT'T FORGET you I promised you, with these flowers I hold in my hand." -Forget-me-nots
"Even if we won't meet again, in new BIRTH we'll join our hands." -Daffodil

With the hint given from alphabet to number code using the flower initial we can assume
that it's telling us to give the flowers initials of meanings that come in order and
translating the initials into numbers.
Astilbe =1
Craspedia = 3
Ziniia's = 26
Forget-me-nots = 6
Daffodils = 4

and so the answer would be: 132664

The teleportation puzzle, the top left area gets you to the middle room if you take the bottom right warp
And the left warp in the middle area gets you to the door