Because of the play at home initiative, DE is offering the starter bundle completely for free even without ps+, you cant (as of right now) get it from the in game store so you have to get it from the PlayStation store, if you have bought it in the past you can claim it again (i dont know if you get everything or just the bonus) this bundle includes:
100 Platinum
100,000 Credits
1 Orokin Reactor
1 Orokin Catalyst
1 Warframe Slot
2 Weapon Slots
1 Essential Base Damage Mod Bundle
7-Day Affinity Booster
7-Day Credit Booster
Pyra Syandana
Kumuda Glyph & Sigil
BONUS: Liset Zikha Skin
An exclusive new adornment for your Landing Craft. (Once the promotion ends, you will no longer be able to get this)
For more (well, basically the same info) click here